1. Technical Field
The present invention relates to a liquid ejecting head including a piezoelectric element that causes a change in the pressure in a pressure-generating chamber communicating with a nozzle opening and that includes a piezoelectric layer and electrodes configured to apply a voltage to the piezoelectric layer, and a liquid ejecting apparatus including the liquid ejecting head.
2. Related Art
A known piezoelectric element used in a liquid ejecting head has a structure in which a piezoelectric layer composed of a piezoelectric material having an electromechanical conversion function, for example, a crystallized dielectric material is sandwiched between two electrodes. Such a piezoelectric element is mounted on a liquid ejecting head as an actuator device of a flexural oscillation mode, for example. A typical example of the liquid ejecting head is an ink jet recording head in which a part of a pressure-generating chamber communicating with a nozzle opening that ejects ink droplets is made up of a diaphragm, this diaphragm is deformed using a piezoelectric element to apply a pressure to ink in the pressure-generating chamber, thereby ejecting the ink as ink droplets from the nozzle opening.
A high piezoelectricity is required for piezoelectric materials used as a piezoelectric layer (piezoelectric ceramic) constituting such a piezoelectric element. A typical example of the piezoelectric materials is lead zirconate titanate (PZT) (refer to JP-A-2001-223404).
However, from the standpoint of environmental issues, there has been a requirement of a piezoelectric material having a reduced content of lead. As for a lead-free piezoelectric material, for example, JP-A-2008-069051 discloses piezoelectric ceramics having a chemical composition represented by x[(BiaK1-a)TiO3]-(1-x)[BiFeO3] (wherein 0.3≦x≦0.8 and 0.4<a<0.6).
The piezoelectric ceramics described in JP-A-2008-069051 are so-called bulk ceramics having a film thickness of 0.1 mm. In the case where this material is formed into a thin film, it is difficult to use the material in a liquid ejecting head because of its low insulating property and large leakage current. This problem occurs not only in an ink jet recording head that ejects ink but also in other liquid ejecting heads that eject droplets of a liquid other than ink.